The present invention relates to a process for preparing a rice nectar, more specifically, a process for preparing an instant rice nectar that can be preserved for a long time.
Shikhye, a Korean traditional beverage of delicious taste and characteristic flavor, is a rice nectar which has been conventionally prepared by a series of processes, i.e., steeping malt in warm water of a temperature between 30 and 40xc2x0 C. for 1 or 2 hours and extracting malt solution for 1 or 2 hours, adding nectaring rice to the malt solution and saccharifying for 4 to 6 hours, and boiling and chilling. However, said conventional process for preparing Shikhye, has been proven to be less satisfactory in the sense that the scale of manufacture is very restricted and it takes relatively long time to prepare the nectar, i.e., more than 10 hours.
Accordingly, many efforts have been made to develop a simple process for preparing an instant rice nectar; and, a variety of processes have been developed in the art as follows:
Korean Patent Publication No. 89-3698 discloses a process for preparing an instant rice nectar, in which the step of preparing malt solution is greatly simplified, by extracting the malt solution from malt which is contained in a heat sealable paper bag. Korean Patent Publication No. 89-4273 teaches a process for preparing an instant rice nectar, in which both malt contained in a heat sealable paper bag and dried nectaring rice are steeped in water at the same time and extracted for 4 to 6 hours, and then saccharified.
However, said prior art processes have had shortcomings that the time-consuming saccharification step of malt often deteriorates the quality of malt and the total amount of the product is very limited. Moreover, the final product thus manufactured has not been readily commercialized, since long-term preservation of the rice nectar was impossible.
Under the circumstances, the present inventors have developed a novel process for preparing an instant rice nectar, in which: saccharification of malt is greatly simplified by incubating a mixture of malt extract and nectaring rice with starch hydrolase, which raises the efficiency of saccharification while preventing deterioration of malt during the manufacturing process, and long-term preservation of the rice nectar is also guaranteed by employing a retort sterilization, thereby enabling mass production and commercialization of the instant rice nectar.
The primary object of the present invention is, therefore, to provide a process for preparing an instant rice nectar that can be preserved for a long time while preventing deterioration of malt, thereby enabling mass production and commercialization.
The process for preparing the instant rice nectar of the invention comprises the following steps, where the weight percentage(wt %) of the employed materials is represented on the basis of the weight of the final product:
Step 1: Extraction and Saccharification of Malt
15 to 35 wt % of water is placed in a mixer, of which the temperature is maintained between 10 and 50xc2x0 C., and malt is added to the water. The resulting mixture is subjected to stirring for 0.5 to 2 hours under the same temperature and filtrated to obtain malt extract. The malt extract thus prepared is heated up to 40 to 70xc2x0 C. and saccharified by incubating with starch hydrolase for 1.5 to 4 hours. Then, the saccharified malt extract is heated again up to the boiling point, i.e., 90 to 105xc2x0 C., and left to stand for 2 to 10 minutes and to chill down to 65 to 75xc2x0 C. The saccharified solution is, in turn, filtrated, and to the filtrate is added 7 to 15 wt % of white sugar to bring the total sugar content to Brix value between 32 and 68. Preferably, 2 to 4 wt % of malt is added and 0.001 to 0.1 wt % of starch hydrolase such as xcex1- and xcex2-amylases is employed in this step; and, 0.05 to 0.3 wt % of ginger, a flavor enhancer, is further added to the saccharified malt extract under heating. Impurities in the malt extract solution are removed, if necessary.
Step 2: Preparation of Nectaring Rice and Saccharification
3 wt % of nonglutinous rice is washed with water two or three times to remove impurities, and steeped in water and boiled for one hour to gelatinize, and then left to stand to yield nectaring rice. One to three times of water by weight maintained at a temperature between 40 and 70xc2x0 C. is added to the nectaring rice together with starch hydrolase and incubated under a temperature between 40 and 70xc2x0 C. for 1.5 to 4 hours to saccharify the rice. Then, the saccharified nectaring rice is collected and washed with water. Preferably, xcex1-amylase and xcex2-amylase of 0.01 to 0.1 wt % each are employed as starch hydrolases.
Step 3: Filling-up
The malt extract saccharified in
Step 1 is diluted with water so that the solution""s sugar content ranges from Brix 10 to 14, and mixed with the nectaring rice saccharified in Step 2. Then, the resulting rice nectar is filled up in a proper container and sealed under vacuum condition.
Step 4: Retorting
The rice nectar in a container of Step 3 is put in a retort chamber and sterilized under a pressure of 1.2 to 1.5 kg/cm2 and a temperature of 110 to 125xc2x0 C. for 10 to 30 minutes, preferably, for 13 to 25 minutes. In this step, pathogenic microorganisms in raw materials or contaminated in manufacturing processes, especially spore-forming bacteria, such as Bacillus and Clostridium which do not live longer than 5 to 6 minutes at 120xc2x0 C., can be completely eliminated by being subjected to said temperature for 10 to 30 minutes, preferably, for 13 to 25 minutes. After retorting, the instant rice nectar can be preserved for more than 12 months.
The present invention is further illustrated in the following examples, which should not be taken to limit the scope of the invention.